ADAPTED WAVELENGTH METHODS FOR IN-SITU ELLIPSOMETRY

For real time ellipsometry monitoring, the choice of measurement of wa velength can be advantageously adapted to the controlled parameter. Ad apted wavelength ellipsometry is illustrated here by two examples. Fir stly, a simple method based on the choice of an appropriate wavelength for thickness control is presented. This method requires no informati on on the underlaying structure and is well suited to control depositi on of multilayer stacks such as Bragg reflectors. Examples of fabricat ion control are presented. Secondly, we report results of temperature measurements. Semiconductor spectroscopic ellipsometry had shown that there is a wavelength range within which the optical response is relat ively insensitive to temperature and that there are other wavelengths in which it is highly sensitive. Thus, according to the wavelength, el lipsometry can be used to measure temperature, or, to measure other pa rameters taking the temperature effect into account. (C) 1998 Elsevier Science S.A.